Biomedical subjects

Y Jiao

Publications and source records attributed to Y Jiao.

At least 19 recordsLinked to original sources

PubMed2001

Dynamic interactions of p53 with DNA in solution by time-lapse atomic force microscopy.

Dynamic interactions of the tumor suppressor protein p53 with a DNA fragment containing a p53-specific recognition sequence were directly observed by time-lapse tapping mode atomic force microscopy (AFM) in liquid. The divalent cation Mg(2+) was used to loosely attach both DNA and p53 to a mica surface so they could be imaged by the AFM while interacting with each other. Various interactions of p53 with DNA were observed, including dissociation/re-association, sliding and possibly direct binding to the specific sequence. Two modes of target recognition of p53 were detected: (a) direct binding, and (b) initial non-specific binding with subsequent translocation by one-dimensional diffusion of the protein along the DNA to the specific site.

Aluminum Silicates↗

PubMed2001

[Significance of her2 oncogene expression in primary nasopharyngeal carcinoma].

OBJECTIVE: To investigate the status of her2 oncogene at DNA level and the molecular mechanism of overexpression of her2 oncoprotein in part of patients with nasopharyngeal carcinoma (NPC). METHODS: Forty-five cases of PNC tissue and fifteen cases of normal epithelial tissue adjacent to tumor tissue were examined for her 2 signal and centromere 17 signal. Interphase fluorescence in situ hybridization (FISH) was used to examine the copy number of her 2 and immunohistochemical (IHC) staining were used to analyze the copy number and protein expression of her2. RESULTS: There were 1.92% +/- 0.10% her2 signals per nucleus in normal epithelial tissue adjacent to tumor. 75.52 +/- 9.33% of the nuclei contained 2 her2 signals and 2 centromere 17 signals. No alteration in gene copy number was found in cancerous nuclei. However, IHC staining of the 45 tumors with antibody against her2 showed that overexpression of her2 oncoprotein occurred in 33% (15/45) of NPC. However, there was no significant correlation between her2 expression and sex, age, clinical staging, and clinical outcome of patients. CONCLUSION: The overexpression of her2 in NPC does not relate to her2 gene amplification. Immunohistochemistry may not be a good measure to examine her2 expression. The mechanism of her2 oncoprotein overexpression and its biological significance in the development of NPC remain to be elucidated.

Adult↗

PubMed2001

A new glycogen synthase activity ratio in skeletal muscle: effects of exercise and insulin.

It was recently reported that MnSO4 stimulates glycogen synthase-dependent glucose transfer from UDPglucose into trichloroacetic acid precipitable endogenous glycoproteins (GSMn(T)) in human muscle extracts. To determine the physiologic significance of this reaction, we compared a new GS activity ratio, GSMn(T)/GSH(E) (where GSH(E) represents the usual glucose transfer to ethanol precipitable exogenous glycogen by GS at 7.2 mM glucose 6-phosphate), with the generally used GSL(E)/GSH(E) ratio (where GSL(E) represents glucose transfer at 0.17 mM glucose 6-P concentration). Biopsies were obtained from the quadriceps femoris muscle of healthy subjects at rest, after 40 min of bicycle exercise at approximately 65% of maximal oxygen uptake and after isometric contraction at 2/3 maximal force to fatigue (approximately 1 min). GSMn(T)/GSH(E) increased from 0.012+/-0.002 at rest to 0.054+/-0.008 (P<0.01) after 40 min of bicycle exercise and the increase in GSMn(T) activity was strongly related to the decrease in endogenous glycogen (i.e.. increase in short-chain endogenous glycoproteins) (r=0.90; P<0.05). On the other hand, GSL(E)/GSH(E) did not change significantly after bicycle exercise (rest = 0.49+/-0.04; exercise = 0.58+/-0.08, P>0.05). GSMn(T)/GSH(E) increased from 0.010+/-0.001 at rest to 0.016+/-0.002 (P<0.05) after isometric exercise, whereas GSL(E)/GSH(E) decreased from 0.27+/-0.04 to 0.20+/-0.02 (P<0.05) under corresponding conditions. Last, insulin, which stimulates glycogen synthesis, also increased GSMn(T)/GSH(E) (1.8-fold, P<0.05), as well as GSL(E)/GSH(E) (1.4-fold, P<0.05), in isolated rat soleus muscle. These data indicate that GSMn(T)/GSH(E) is influenced by endogenous substrate availability and covalent modification. Therefore, GSMn(T)/GSH(E) ratio may prove to be a useful alternative to other GS activity ratios that only reflect changes in the phosphorylation state of GS.

Exercise↗

PubMed2001

Functional receptor-channel coupling compared in contractile and proliferative human vascular smooth muscle.

We have previously identified a human vascular smooth muscle clone that can reversibly convert between proliferative and contractile phenotypes. Here we compared receptor-channel coupling in these cells using fura-2 to monitor [Ca(2+)](i) and patch-clamp to record currents. Histamine elevated [Ca(2+)](i) in all cells and caused contraction of cells exhibiting the contractile phenotype. The rise of [Ca(2+)](i) persisted in Ca(2+)-free solution and was abolished by thapsigargin, indicating involvement of stores. Whole cell electrophysiological recording revealed that histamine evoked transient outward K(+) current, indicating functional receptor-channel coupling. The time-course and amplitude of the histamine-activated current were similar in cells of the proliferative and contractile phenotypes. Moreover, a large conductance K(+) channel was recorded in cell-attached patches and was activated by histamine as well as the Ca(2+) ionophore A-23187, identifying it as the large conductance Ca(2+)-dependent K(+) channel. This K(+) channel showed similar characteristics and activation in both proliferative and contractile phenotypes, indicating that expression was independent of phenotype. In contrast, histamine also elicited an inward Cl(-) current in some contractile cells, suggesting differential regulation of this current depending on phenotype. These studies demonstrate the usefulness of this human vascular cell clone for studying functional plasticity of smooth muscle, while avoiding complications arising from extended times in culture.

Calcimycin↗

PubMed2001

Altered glycogen synthase and phosphorylase activities in skeletal muscle of tetraplegic patients.

Despite marked differences in both the extent of physical activity and in muscle metabolism and structure between tetraplegic and control subjects, the glycogen content in the skeletal muscle of both groups is similar. We determined whether this similarity could be explained by the activities of key enzymes of glycogen metabolism. Muscle biopsies were analysed for glycogen synthase (GS) and glycogen phosphorylase (GP) activities, as well as for metabolites. Glycogen content did not differ significantly between the two groups. Total glycogen synthase activity was reduced by almost 60 % in tetraplegics (P < 0.01), whereas total phosphorylase activity did not differ between groups. GS fractional activity did not differ between groups, whereas phosphorylase fractional activity (-/+ AMP) was significantly higher in the tetraplegics (0.08 +/- 0.01, control; 0.25 +/- 0.02, tetraplegics; P < 0.001). Neither uridine diphosphate (UDP)-glucose nor glucose 6-phosphate (G-6-P) content in muscle differed significantly between groups. These data demonstrate that, in tetraplegics, muscle glycogen content is preserved despite decreases in GS activity and increases in phosphorylase fractional activity. Muscle paralysis has differential effects on the activities of GS and GP. Experimental Physiology (2001) 86.2, 205-209.

Adult↗

PubMed2001

[Interleukin-1 increase nitric oxide synthesis through up-regulation of inducible nitric-oxide synthase by rabbit mandibular condylar cartilage cells in vitro].

OBJECTIVE: To investigate the influence of IL-1 on the biosynthesis of nitric oxide by rabbit mandibular condylar cartilage (MCC) cells. METHODS: MCC cells of white rabbits were harvested enzymatically and cultured in DMEM supplemented with 0.4% newborn calf serum. In the experiment, a variety of concentrations of IL-1 were added to the medium. NO production was determined as nitrite accumulation in the medium. The effects of IL-1 on the mRNA levels of inducible nitric-oxide synthase (iNOS) were assessed by mRNA in situ hybridization method. RESULTS: IL-1 can significantly increase nitric oxide synthesis by MCC cells in a concentration-dependent manner. In addition, normal MCC cells had light expression of iNOS expression and IL-1 (10-100 micrograms/L) promoted the expression of iNOS. CONCLUSIONS: IL-1 can inhibit the chondrocytes proliferation and induce apoptosis that might be through the way of up-regulation of iNOS expression.

Animals↗

PubMed2001

[Study on nuclear DNA content and image cytometry in cervical cancer and precursor lesions].

OBJECTIVE: The aim of this research was to study the biological and clinical features of cervical cancer and precursor lesions. METHODS: Nuclear DNA was analyzed by image cytometry (ICM) in 125 embedded tissue 5 microns sections stained with Feulgen stain. Samples included normal cervical squamous epithelium (n = 11), cervical intraepithelial neoplasia I (CIN I) (n = 22), CINII (n = 17) and CINIII (n = 13), cervical neoplasm (n = 62). RESULTS: The mean DNA content, nuclear area increased progressively from normal cervical epithelium, CINI, CINII, CINIII to invasive squamous carcinoma. Statistical analysis revealed significant difference (P < 0.05, < 0.01). Histograms of cellular DNA ploidy distribution showed different pattern, where 9 components (9C) cells were observed in cervical cancer and CINIII. No differences in DNA mean ploidy (DMP), DNA index (DI) and nuclear area were observed between cervical neoplasm. CONCLUSIONS: It is increased progressively from normal cervical epithelium to cancer, in which CINIII is turning point.

Adult↗

PubMed2001

[Culture and cryopreservation of human mandibular condylar cartilage cells].

OBJECTIVE: To establish an effective way in cryopreserving mandibular condylar cartilage cells. METHODS: Human mandibular condylar cartilage (MCC) cells were harvested and amplified by microcarrier culture technique. MCC cells were preserve in liquid nitrogen. The biological properties of cryopreserved MCC cells were investigated. RESULTS: Cells from liquid nitrogen preservation kept their phenotypic, proliferative an metabolic characteristics of MCC cells in vivo. CONCLUSIONS: Cryopreservation of MCC cells can supply adequate qualified cells for repairing the defects of mandibular condyle cartilage and temporomandibular joint disk.

Cartilage↗

PubMed2000

Genetic alterations in DNA diploid, aneuploid and multiploid colorectal carcinomas identified by the crypt isolation technique.

Loss of heterozygosity (LOH) and microsatellite instability (MSI) commonly occur in colorectal carcinomas. However, the role of these genetic alterations in determining DNA ploidy status of tumors (diploid, aneuploid and multiploid) remains unclear. In the present study, we attempted to clarify the relationship between genetic alterations and DNA ploidy status. Crypt isolation coupled with DNA cytometric sorting and polymerase chain reaction assay (17 microsatellite markers) were used to study allelic losses and MSI in 59 colorectal carcinomas (diploid, 15; aneuploid, 10 and multiploid, 34). Of the 15 diploid carcinomas, 6 exhibited MSI in which allelic losses were rarely found. The other 9 diploid tumors mostly exhibited allelic losses, but none displayed MSI status. Whereas allelic losses frequently occurred in the aneuploid carcinomas and the aneuploid populations of multiploid carcinomas, they were rarely detected in the diploid populations of multiploid carcinomas. MSI status was not observed in aneuploid carcinomas nor in either population of multiploid carcinomas. Although multiploid carcinomas genetically resemble aneuploid carcinomas in the expression of the severe LOH phenotype, the genetic alterations seen in the diploid populations of multiploid carcinomas may differ from those of diploid carcinomas. Furthermore, all diploid, aneuploid and both the diploid and aneuploid fractions of the multiploid tumors that were non-MSI exhibited a high rate of LOH, suggesting that LOH is independent of the tumor's ploidy status.

Adenocarcinoma↗

PubMed2000

Pathway tracing using biotinylated dextran amines.

Biotinylated dextran amines (BDA) are highly sensitive tools for anterograde and retrograde pathway tracing studies of the nervous system. BDA can be reliably delivered into the nervous system by iontophoretic or pressure injection and visualized with an avidin-biotinylated HRP (ABC) procedure, followed by a standard or metal-enhanced diaminobenzidine (DAB) reaction. High molecular weight BDA (10 k) yields sensitive and exquisitely detailed labeling of axons and terminals, while low molecular weight BDA (3 k) yields sensitive and detailed retrograde labeling of neuronal cell bodies. The detail of neuronal cell body labeling can be Golgi-like. BDA tolerates EM fixation and processing well and can, therefore, be readily used in ultrastructural studies. Additionally, BDA can be combined with other anterograde or retrograde tracers (e.g. PHA-L or cholera toxin B fragment) and visualized either by multi-color DAB multiple-labeling - if permanent labels are desired, or by using multiple simultaneous immunofluorescence - if fluorescence viewing is desired. In the same manner, BDA pathway tracing and neurotransmitter immunolabeling can be combined. Note that BDA pathway tracing can also be combined with anterograde or retrograde labeling with fluorescent dextran amines, if one wishes to exclusively use tracers with the favorable transport properties and sensitivities of dextran amines. In this case, the BDA can be visualized together with the fluorescent dextran amines using fluorescence labeling for the BDA, or the fluorescent dextran amines can be visualized together with the BDA by multicolor DAB labeling via immunolabeling of the fluorescent dextran amines using anti-fluorophore antisera. BDA is, thus, a flexible and valuable pathway tracing tool that has gained widespread popularity in recent years.

Animals↗

PubMed2000

Identification of the anterior nucleus of the ansa lenticularis in birds as the homolog of the mammalian subthalamic nucleus.

In mammals, the subthalamic nucleus (STN) is a glutamatergic diencephalic cell group that develops in the caudal hypothalamus and migrates to a position above the cerebral peduncle. By its input from the external pallidal segment and projection to the internal pallidal segment, STN plays a critical role in basal ganglia functions. Although the basal ganglia in birds is well developed, possesses the same major neuron types as in mammals, and plays a role in movement control similar to that in mammals, it has been uncertain whether birds possess an STN. We report here evidence indicating that the so-called anterior nucleus of the ansa lenticularis (ALa) is the avian homolog of mammalian STN. First, the avian ALa too develops within the mammillary hypothalamic area and migrates to a position adjacent to the cerebral peduncle. Second, ALa specifically receives input from dorsal pallidal neurons that receive input from enkephalinergic striatal neurons, as is true of STN. Third, ALa projects back to avian dorsal pallidum, as also the case for STN in mammals. Fourth, the neurons of ALa contain glutamate, and the target neurons of ALa in dorsal pallidum possess AMPA-type glutamate receptor profiles resembling those of mammalian pallidal neurons. Fifth, unilateral lesions of ALa yield behavioral disturbances and movement asymmetries resembling those observed in mammals after STN lesions. These various findings indicate that ALa is the avian STN, and they suggest that the output circuitry of the basal ganglia for motor control is similar in birds and mammals.

Animals↗

PubMed2000

Ultrastructural architecture and mechanical properties of attachment pads in Tettigonia viridissima (Orthoptera Tettigoniidae).

Natural releasable attachment systems of insect legs, where attachment-detachment performances are often very fast, seem to be optimized to get a maximum of real contact to the substratum. Tarsi of Tettigonia viridissima bear flexible attachment pads with unusual ultrastructural architecture of the cuticle. The indentation of the attachment pads was measured under different loads using a force-tester. Since the mechanical properties are influenced by material structure, the freeze-substitution experiments were undertaken to investigate the influence of loads on material structure. Both profile changes of the surface and the orientation of cuticle microfibrils were visualized by means of scanning electron microscopy followed by fracturing of the frozen material. The results show that the flexible pad material deforms replicating the substrate profile down to the micrometer roughness. The pad material showed both elastic and viscous behavior under loads. Elastic deformation of the pad occurred under normal force applied for 4-6 s (elastic modulus 27.2 +/- 11.6 kPa). Two viscous relaxation processes were found, of time constants tau1 = 1.88+/-0.616 s and tau2 =41.2 +/- 9.95 s. Low stiffness of material studied here aids in surface replication and increase of area of real contact between the pad and the underlying substrate.

Animals↗

PubMed2000

Adhesion measured on the attachment pads of Tettigonia viridissima (Orthoptera, insecta).

The tarsi of the cricket Tettigonia viridissima bear flexible attachment pads that are able to deform, replicating the profile of a surface to which they are apposed. This attachment system is supplemented by a secretion produced by epidermal cells and transported onto the surface of the pad through the pore canals of the pad cuticle. This study shows that the secretion alone is necessary, but not sufficient, for adhesion. To account for the full adhesive force, the deformation of the pad and the resulting changes in contact area were considered. In two series of experiments, the adhesive properties of the secretion and the adhesion of the whole pad were measured using a force tester, the sensitivity of which ranged from micronewtons to centinewtons. The adhesive forces of the secretion measured between a smooth sapphire ball with a diameter of 1.47 mm and a flat silicon surface ranged from 0.1 to 0.6 mN. In a control experiment on the silicon surface without secretion, no adhesive force was measured. There was no dependence of the adhesive force on the applied compressive force. When an intact pad was pulled off a flat silicon surface, the adhesive force increased with increasing applied compressive force, but it did not increase further once the applied force exceeded a certain value. The saturated adhesive force, ranging from 0.7 to 1.2 mN, was obtained at applied forces of 0.7-1.5 mN. The hemispherical surface of the pad had a larger contact area and demonstrated greater adhesion under a larger applied force. Adhesion became saturated when a pad was deformed such that contact area was maximal. The tenacity (the adhesive force per unit area) was 1.7-2.2 mN mm(-)(2).

Adhesiveness↗

PubMed2000

[Evaluation of plant protectants against pest insects].

An interference index of population control (IIPC) was constructed for investigating the complex effects of plant protectants, including the effects of repelling insect pests away from the plant, deterring the egg laying of adults and the continuation of feeding, and causing death by toxicity. At the same time, indicated by IIPC, the alcohol extracts of some common plants, such as Eucalytus rubusta, Wedelia chinensis etc. and the neem oil gave very good results to protect the plant against Plutella xylostella. The D-C-Tron NR Petroleum Spray Oil (CALTEX) also gave an excellent effect to protect citrus against red mite. All the experiments show the important role of the repellent effect on the pests.

Animals↗

PubMed2000

[Effects of various growth factors on human mandibular condylar cartilage cell proliferation].

OBJECTIVE: To investigate the effects of transforming growth factor-beta 1 (TGF-beta 1) insulin-like growth factor I (IGF-I) and basic fibroblast growth factor(bFGF) on human mandibular condylar cartilage (MCC) cell proliferation. METHODS: Isolated human MCC cells were cultured in DMEM supplemented with 10% newborn calf serum(NCS). The second passages were used in order to avoid chondrocyte dedifferentiation. Cells were seeded at 2 x 10(4)/well on 96-well plate. After synchronization, medium was replaced by DMEM containing 0.4% NCS or 10% NCS with various growth factors, concentrations and combinations. Dose-response and time-course were studied by MTT colorimetric method. RESULTS: In 0.4% serum containing medium, bFGF stimulated the proliferation moderately, whereas TGF-beta 1 and IGF-I had less effect. In 10% NCS condition, all three growth factors had mitogenic effect and acted dose-dependently. The effects were significant after three days. Among them, bFGF was a potent mitogen(increased by 65%), IGF-I the next(24%). The effect of TGF-beta 1 (13%) might be mediated by some other factors in the serum. The synergetic effects were achieved when they were used in combination. CONCLUSION: It is suggested that optimal combination of growth factors can promote the proliferation of MCC cells significantly, this might be an ideal way in dealing with cartilage damage during pathogenesis.

Cartilage↗

PubMed2000

[A quick way in isolation and amplification of mandibular condylar cartilage cell in vitro].

OBJECTIVE: To establish a quick way in acquiring well differentiated mandibular condylar cartilage (MCC) cells with high viability in large scale. METHODS: Japan white rabbit MCC cells were harvested by enzymatic method. They were grown in a modified bioreactor culture system, which contained the cytodex-3 micro-carriers in the culture medium. Kinetic growth of MCC cells on DEAE-dextran micro-carrier was observed under phase contrast microscope and environmental scanning microscope respectively. RESULTS: MCC cells attached rapidly to the surface of micro-carriers, but their spreading was slow. A quick growth of these cells was observed when they fully spread onto the micro-carrier. The number of MCC cells increased 16.2 times compared with that of plating. CONCLUSIONS: Micro-carrier culture of MCC cells can yield a large quantity of cells within a short period of time that will be of benefit in banking MCC cells for reconstruction of impaired cartilage.

Animals↗

PubMed2000

[Fibronectin in adhesion, spreading and proliferation of mandibular condylar cartilage cells on cytodex-3 microcarrier].

OBJECTIVE: The purpose of this study was to investigate the effects of exogenous fibronectin on the attachment and growth of mandibular condylar cartilage (MCC) cells on DEAE-dextran micro-carrier. METHODS: MCC cells were harvested from newborn New Zealand white rabbits by sequential digestion with trypsin and collagenase. They were grown on the 20 mg/L fibronectin-coated and uncoated cytodex-3 micro-carrier. Samples were collected after 1, 3, 5, 7, 9, 11 days. The kinetics of adhesion and growth were observed with phase contrast microscope and environmental scanning electronic microscope (ESEM) and quantified by 0.1% crystal violet nuclear extrusion method. RESULTS: MCC cells could rapidly attach and spread onto the fibronectin-coated cytodex-3, and nearly 60 percent cells attached to the micro-carrier within 2 hours. Spreading cells were flat and lowly refractile observed under phase contrast microscope. While the attachment and spreading of the cells in the untreated group were slow, and only 36 percent cells attached to the uncoated micro-carrier. However, most cells attached to the micro-carrier in both groups after 24 hours. The MCC cells attaching to FN-coated cytodex-3 observed under ESEM were flatter and adhered tightly with more processes (pseudopodia) stretching out from cytoplasm. In contrast, cells on untreated cytodex-3 remained regularly round even 24 hours after being plated. Meanwhile, there was an accelerated growth rate of the MCC cells on the fibronectin treated cytodex-3. The cell density in the FN treated group was higher than that of the untreated group at the end of the culture. CONCLUSION: Fibronectin, one major glycoprotein of extracellular matrix, plays an important role in cell attachment and spreading. The better understanding of the extracellular matrix will be helpful in selecting the optimal substrate for cell growth in vitro.

Adhesiveness↗

PubMed2000

[The regulation effects of growth factors on the procollagen gene expressions of human mandibular condylar cartilage cells].

OBJECTIVE: At the early stage of osteoarthrosis (OA) and joint damage, the cartilage cells proliferation increases dramatically, but this repair process is finally replaced by the progressive destruction of the cartilage. The reason, in accordance to the latest research, is the abnormal phenotype of the involved cartilage cell. This result suggests that the regulation of cartilage cell phenotype may be an effective way in the treatment of OA and other cartilage destructive diseases. In this study, the effects of transforming growth factor-beta(TGF-beta), insulin-like growth factor-I (IGF-I) and basic fibroblast growth factor (bFGF) on collagen expression of human mandibular condylar cartilage cells was investigated. METHODS: Chondrocytes were isolated from human fetus by enzymatic method. The second passage of the cells was used in this study. They were cultured in DMEM medium supplemented with 20% newborn calf serum (NCS). After the cells reached confluence, the medium was replaced by DMEM containing 0.4% NCS. Then the cells were exposed to different growth factors including IGF-I (10 ng/ml), TGF-beta (5 ng/ml) and bFGF (50 ng/ml). The steady state mRNA levels of different samples were examined by slot-blot hybridization. The results were analysed by Student t test. RESULTS: IGF-I had the least effects on the mRNA levels of three kinds of procollagen (type I, type II and type III). On the other hand, bFGF and TGF-beta could inhibit the expression of type II collagen by 0.352 and 0.685 times comparing with the control groups separately. TGF-beta increased type I collagen expression. Besides, bFGF and TGF-beta also increased the value of type I collagen/type II collagen. None of the three kinds of growth factors had obvious effects on the expression of type III collagen. CONCLUSION: IGF-I can maintain the chondrocyte differentiated phenotype, while TGF-beta and bFGF have inhibitory effects.

Cells, Cultured↗